Blue whales are growing quieter — and scientists are concerned it may indicate deeper problems in the ocean.
Recent studies have shown that these massive creatures, the largest animals on Earth, are vocalizing much less than they did in the past. Research conducted in New Zealand’s South Taranaki Bight (2016–2018) and the California Current (2015–2020) monitored the whales’ deep, rhythmic calls used for feeding and attracting mates. Both studies reported significant decreases in vocal activity, particularly during years marked by extreme marine heatwaves, when krill — their main food source — became scarce.
As krill populations dropped, blue whales seemed to devote more time to searching for food and less time to calling for mates. Scientists say this shift in behavior highlights the impact of warming oceans and changing ecosystems on whale life. Rising sea temperatures not only place stress on krill but also cause them to disperse and contribute to toxic algal blooms, making conditions even more challenging for marine species.
While humpback whales appear to adjust more easily, blue whales — due to their smaller populations and strong dependence on dense krill swarms — may face heightened risks. Researchers caution that the increasing silence of blue whales could be an early warning sign of broader ecological disruption occurring in the oceans.